Preparation
1. Preheat the oven to 205 Celsius, and line a baking sheet with parchment paper.
Toss the Brussels sprouts with the oil, a pinch of salt and pepper, and the lemon juice, and roast until golden and tender, about 25-30 minutes.
2. While Brussels sprouts roast, prepare your sauce: place a medium-size sauce pan over medium-low heat, and add in the butter and the garlic; once butter is melted and garlic is aromatic, sprinkle in the flour and whisk to blend to make a smooth paste, or "roux", and cook that for about 30 seconds; gradually add in the milk, whisking all the while to avoid lumps, and bring to a vigorous simmer, whisking occasionally; reduce the heat and allow the milk mixture to gently simmer for a few minutes to thicken up; turn off the heat, add the parmesan and whisk that in until smooth; check to see if additional salt is needed; set aside.
3. Prepare breadcrumbs by combining the ingredients in a small bowl, and set aside.
4. To finish, turn your oven on to "broil"; add your roasted Brussels sprouts to a shallow, oven-safe baking dish in a single layer, and crumble over about half of your chopped bacon; drizzle the creamy parmesan sauce over top, then sprinkle over the panko breadcrumbs, and broil for several minutes until everything is golden-brown and crisp.
5. Finish the dish by sprinkling over the rest of the bacon, as well as the thyme leaves, and serve.